The youngster turned 20 today and celebrated by netting the only goal in a 1-0 victory over Genoa.
"I am moved, as it's the best birthday of my life," he told Sky Sport Italia.
El Shaarawy refused to celebrate as a sign of respect for his former fans.
"I am excited and happy, both for the victory and the goal. Is this my Milan? I'm happy people are saying that. I just try to give my all and put myself at the disposal of the Coach."